Sudden cardiac death is the leading cause of death in the United States. Most sudden cardiac deaths are caused by ventricular fibrillation, in which the heart's muscle fibers contract without coordination, thereby interrupting normal blood flow into the body. The best known effective treatment for ventricular fibrillation is electrical defibrillation, in which an electrical pulse is applied to the patient's heart. The electrical pulse must be delivered within a short time after onset of ventricular fibrillation in order for the patient to have any reasonable chance of survival.
The current trend in the medical industry is to make life-saving portable medical devices, such as automated external defibrillators (AEDs), more widely accessible so that patients in need can be treated as quickly as possible. As the availability of portable medical devices continues to increase, more places will have these devices for use in emergency situations, such as in homes, police cars, worksites, and public gathering places. This increase also comes with the heightened likelihood that these portable medical devices will be used by people without medical training or people who are minimally trained in the handling of the medical devices. At the same time, the benefit of having life-saving medical devices immediately available in many places is not fully realized unless the medical devices can be promptly activated and used quickly in case of emergency. Therefore, a portable medical device, such as an AED, must be configured such that even a lay person can intuitively and quickly activate and use the medical device.
A medical device may automatically instruct an operator how to properly operate the medical device via various user interface components. For example, an AED may include a voice command system, a screen command system, and/or various graphics visible to the operator. Additional user interface components may also be available. For example, an AED typically includes a pair of defibrillation electrodes to be applied by an operator on the patient's body. Ideally, various user interface components should be immediately available to the operator of a medical device so that the operator can access or follow instructions offered by the user interface components to operate the medical device to save the patient's life. At the same time, some of the user interface components should be made available to the operator at the appropriate points during treatment of the patient in order to ensure that an instructional command, for example a voice prompt, of the medical device can timely guide the operator how to properly operate the device and treat the patient. This feature can be particularly helpful when the medical device is likely to be used by a lay person who is not very familiar with the medical device and thus needs to rely on commands issued by the medical device to properly handle the medical device.